GC021 Upper Respiratory Tract Infections
Upper respiratory tract infections are acute infections affecting the nasal passages, pharynx, larynx, and sinuses, most commonly caused by viruses, presenting with symptoms such as nasal congestion, sore throat, cough, and malaise.
Upper Respiratory Tract Infections (URTIs)
This lecture (GC 021 / WCS 129) uses URTI—ranked first in a historical Hong Kong primary-care survey—to teach a common consultation. The core message is deceptively simple but exam-critical: most uncomplicated cases are viral and self-limiting and generally do not need antibiotics, investigations or aggressive pharmacotherapy. The examiners test whether you can (1) define and classify URTIs, (2) distinguish them from serious mimics, (3) apply evidence-based (often non-) treatment, (4) use the Centor/McIsaac criteria correctly, (5) manage influenza including vaccination and antivirals, and (6) counsel on prevention.
Learning Objectives (directly from the lecture): [1]
- Define URTIs
- Be familiar with one of the commonest health problems
- Problem-solve common respiratory symptoms
- Diagnose URIs
- Evidence-based management of URTIs
This topic integrates with GC 106 (antibiotic stewardship), GC 052 (fever & purulent sputum — to differentiate LRTI), GC 215 (nasal conditions & NPC), GC 141 (cough in children), CFB WCS29 (ENT conditions including rhinosinusitis), and GC 101/105 (diagnosis of infections, medically important microbes).
How to use these notes
The burden statistics, drug examples, sore-throat algorithm and influenza programme in this deck are lecture-era material. Sections marked Current-practice correction (reviewed August 2026) use current official guidance; always follow the current Hong Kong formulary, laboratory pathway and seasonal vaccination circular in clinical care.
"Self-limited irritation and swelling of the upper airways with associated cough and no signs of pneumonia, in a patient with no other condition that would account for their symptoms, or with no history of COPD, emphysema, or chronic bronchitis." [1]
"Involve the mucous membranes lining the upper respiratory tract from the nostrils and the mouth to the vocal cords in the larynx, also including the paranasal sinuses and the middle ear." [1]
Why this definition matters: “Simple URTI” is a syndrome label, not a virological diagnosis. Focal chest signs, hypoxaemia, marked tachypnoea, respiratory distress or systemic toxicity should trigger assessment for lower-respiratory or other serious disease. COPD/asthma does not prevent a patient acquiring a viral URTI, but wheeze or deterioration may represent an exacerbation and needs a different assessment. Acute bronchitis involves the tracheobronchial tree and is not anatomically an upper-airway infection, even though it commonly follows the same viral syndrome.
Anatomical scope of the "upper respiratory tract":
- Nostrils → nasal cavity → paranasal sinuses
- Mouth → pharynx (naso-, oro-, hypo-)
- Larynx (down to the vocal cords)
- Middle ear (connected via Eustachian tube)
"> 90% viral; < 10% bacterial" [1]
This single fact drives virtually every management decision.
| Category | Organisms | Key Points |
|---|---|---|
| Viral ( > 90%) | Rhinovirus | Most common cause of common cold (30–50% of cases) |
| Adenovirus | Can also cause pharyngoconjunctival fever | |
| Influenza | Causes a distinct clinical syndrome (ILI) | |
| Parainfluenza | Major cause of croup in children | |
| RSV | Common in infants; leads to bronchiolitis | |
| Coronavirus | Includes seasonal strains and SARS-CoV-2 | |
| Bacterial ( < 10%) | Group A β-haemolytic Streptococcus (GAS) | Most important bacterial cause of pharyngitis |
| Haemophilus influenzae | Can cause sinusitis, otitis media, epiglottitis (type b) | |
| Streptococcus pneumoniae | Sinusitis, otitis media | |
| Branhamella (Moraxella) catarrhalis | Sinusitis, otitis media | |
| Staphylococcus aureus | Nasal vestibulitis, secondary infections |
Why > 90% viral matters clinically: Because antibiotics have zero efficacy against viruses. Prescribing antibiotics for viral URTI exposes patients to side effects and drives antimicrobial resistance — a key learning outcome of GC 106. [2]
Anatomical Site–Organism Map from the Diagram
The sagittal diagram is not saying that appearance alone identifies the pathogen; it links each syndrome to its common differentials:
| Site/syndrome | Organisms shown in the lecture image |
|---|---|
| Nasopharyngitis | Rhinovirus, coronavirus, adenovirus, influenza and parainfluenza |
| Pharyngitis | GAS plus rhinovirus, coronavirus, adenovirus, influenza/parainfluenza, human metapneumovirus, RSV, coxsackievirus and bocavirus |
| Tonsillitis | S. pyogenes; the diagram also lists S. pneumoniae, H. influenzae and S. aureus |
| Sinusitis | S. pneumoniae, H. influenzae and M. catarrhalis |
| Laryngitis | Parainfluenza 1–2; the diagram also lists H. influenzae, M. catarrhalis, S. aureus, group A/G streptococci, C. pneumoniae and M. pneumoniae |
Most undifferentiated acute upper-respiratory illness is still viral; this map is a differential by site, not an indication for routine cultures or empiric antibiotics.
"The most common infection in humans. Annual incidence: 2–3×/year (adults), up to 8×/year (children)." [1]
- Rarely lethal, often self-limiting, short in duration
- Despite this, creates a significant health and economic burden:
- ~900,000 annual attendances at public primary care clinics in HK [1]
- Manpower loss, school absenteeism
- Reason for consultation is usually symptom relief, not cure
"Common problems come first" — this is the family medicine principle. In the HK Primary Care Morbidity Survey 2007–08, URI was the #1 health problem at 26.4% of all consultations. [1]
| Rank | HK Survey 2007–08 (All PC) | Public GOPC |
|---|---|---|
| 1 | URI (26.4%) | Hypertension (25.7%) |
| 2 | Hypertension (10.0%) | URI (12.0%) |
| 3 | DM (4.0%) | DM (10.4%) |
| 7 | Acute bronchitis (2.4%) | — |
| 10 | Allergic rhinitis (1.3%) | — |
How to read the burden slides: The 26.4% URI and 36.2% respiratory figures come from the Hong Kong 2007–08 primary-care morbidity survey. They demonstrate scale and the “common problems come first” principle, but should not be presented as current 2026 prevalence or a universal global ranking.
4. Clinical Presentation
Symptoms usually begin 1–3 days after exposure and last 7–10 days, can persist up to 3 weeks. [1]
| Respiratory Symptoms | Systemic/Infection Symptoms |
|---|---|
| Cough / sputum | Chills |
| Runny nose / sneezing | General malaise |
| Nasal congestion | Fever (usually low-grade) |
| Sore throat | Loss of appetite |
| Hoarseness | Nausea / vomiting |
| Sneezing | Dyspepsia / abdominal pain |
Critical Exam Point
"Not all cough, runny nose & sore throat are URTIs." [1] — This statement appears prominently on the lecture slide. Examiners will present a patient with cough/sore throat and expect you to consider serious differentials before labelling it URTI.
4.2 Symptom Analysis — By Individual Symptom
"Not all cough & phlegm are due to URIs!" [1]
| Category | Conditions to Consider |
|---|---|
| Emergencies | Cyanosis, dyspnoea, drooling (think epiglottitis, foreign body) |
| Serious | Pneumonia, TB, cancer, CHF |
| Pitfalls | Allergic rhinitis, asthma, COPD, bronchiectasis, GERD, drug-induced (e.g. ACEI) |
Cough & phlegm in URTI specifically: [1]
- Acute irritating cough
- Scanty sputum, white/yellow
- Postnasal drip / sore throat
- Daytime & before or after sleeping
- General condition good, no SOB / chest signs
- Self-limiting, lasting 1–3 weeks
Symptom analysis framework — always assess:
- Nature: Dry vs. productive; sputum colour (white/yellow does NOT automatically = bacterial)
- Course: Acute ( < 3 weeks) / subacute (3–8 weeks) / chronic ( > 8 weeks) / recurrent
"Yellow nasal discharge may, but does not necessarily, equal bacterial infection." [1]
This is a classic misconception that examiners love to exploit. The colour of nasal discharge reflects the stage of inflammation and neutrophil activity, not necessarily bacterial involvement.
Differentials for runny nose (not all are common cold): [1]
| Category | Consider |
|---|---|
| Serious | NPC (nasopharyngeal carcinoma) — always consider in southern Chinese with unilateral bloody nasal discharge, serous otitis media, cranial nerve palsies |
| Pitfalls | Allergy, nasal polyps, foreign body (esp. in children — unilateral foul discharge), sinusitis |
| Complications | Otitis media, sinusitis |
Nasal symptoms in URTI specifically: [1]
- Acute onset
- Copious clear watery discharge
- Sneezing ++, relatively little itchiness (cf. allergic rhinitis where itchiness is prominent)
- Little diurnal variation (cf. allergic rhinitis which is often worse in the morning)
- Self-limiting, lasting 3–5 days
"> 90% acute sore throat due to viral URIs" [1]
| Category | Consider |
|---|---|
| Emergency | Acute epiglottitis (drooling of saliva, toxic appearance, "hot potato" voice, stridor) |
| Serious | Bacterial tonsillitis, peritonsillar abscess (quinsy), TB, lymphoma |
| Pitfalls | Postnasal drip, irritation, foreign body, infectious mononucleosis (EBV — think of this in young adults with prolonged sore throat, fatigue, lymphadenopathy, hepatosplenomegaly) |
Key clinical pearls: [1]
- Enlarged tonsils are normal in children — do not over-interpret tonsillar size alone
- Exudates can mean viral OR bacterial — exudate alone does NOT confirm bacterial aetiology (another common exam trap)
- The photograph shows bilateral tonsillopharyngeal erythema/exudate with a central uvula. It does not identify the pathogen. Quinsy is suggested instead by unilateral peritonsillar swelling, uvular deviation, trismus and a muffled voice.
Airway safety: suspected epiglottitis
Drooling, stridor, tripod positioning, severe dysphagia or a toxic appearance requires urgent airway-capable help. Keep the patient calm and upright; do not force a throat examination with a tongue depressor or send an unstable patient unescorted for imaging.
"Indicates pathology in the larynx. Most likely viral URI if acute." [1]
| DDx | Features |
|---|---|
| Vocal cord polyps/nodules | Chronic, associated with voice overuse |
| Acute epiglottitis | Emergency — drooling, stridor, toxic child sitting forward |
| Croup | Barking "seal" cough, inspiratory stridor, typically 6 months–3 years |
| Carcinoma of larynx | Chronic progressive hoarseness in smoker |
| Pitfalls | Sputum retention, laryngeal injury/compression, post-intubation trauma |
5. Centor / Modified McIsaac Criteria for Sore Throat
HIGH YIELD — Frequently Examined
The Centor criteria estimate the probability that pharyngitis is streptococcal and guide management decisions. [1] This is one of the most commonly tested clinical decision tools in URTI.
- History of fever (or temperature ≥ 38°C)
- Tonsillar exudates
- Tender anterior cervical lymphadenopathy
- Absence of cough
Why "absence of cough"? — Cough is a hallmark of viral URTI. Its absence raises the probability of a non-viral (bacterial, i.e. GAS) aetiology. This is a discriminator the examiners love.
- Age 3–14: Add 1 point (GAS pharyngitis is most common in school-age children)
- Age 15–44: Add 0 points
- Age ≥ 45: Subtract 1 point (GAS pharyngitis is uncommon in older adults)
- Score range: −1 to 5
| Score | Action |
|---|---|
| −1, 0, or 1 | No antibiotic or throat culture necessary |
| 2 or 3 | Consider rapid strep testing and/or culture; treat with antibiotic if positive |
| 4 or 5 | Consider rapid strep testing and/or culture; treat if positive |
Current-practice correction (reviewed August 2026)
Centor/McIsaac estimates probability; it does not prove GAS. Current pathways differ. CDC guidance says do not test when clear viral features are present; without viral features, confirm GAS using RADT or culture. In symptomatic children aged 3 years or older, a negative RADT should be backed up by culture; this is not routinely required in adults [10]. NICE instead uses FeverPAIN or Centor to choose no, delayed/back-up or immediate antibiotics without requiring universal microbiological testing [11]. Therefore, “a high score always means test first” is not a universal rule—follow the local pathway and consider rheumatic-fever epidemiology.
If GAS pharyngitis is confirmed, why treat with antibiotics at all?
- Prevent suppurative complications (peritonsillar abscess, retropharyngeal abscess)
- Prevent acute rheumatic fever (ARF) — still relevant in developing countries
- Modestly shorten symptoms and reduce transmission
- First-line when GAS is confirmed/treated: penicillin V or amoxicillin; course and dose follow the local guideline. Penicillin allergy management depends on reaction phenotype, and macrolide/clindamycin resistance varies geographically [10].
6. Transmission & Prevention
"Transmission by contacts & droplets. Maximum viral shedding on D2 & D3. Virus found in 40% hand samples. Natural infectivity rate 38–88%. Median incubation 3 days (range 1–10). 70–90% infected are symptomatic. Diagnosis is clinical; viral culture possible; serology useless." [1]
Key points:
- The slide summarizes an older common-cold transmission study. Respiratory viruses differ: infection can occur through inhaled particles/droplets, direct contact and contaminated hands/surfaces; do not assign one universal “most important” route to every URTI.
- Layer prevention according to context: hand hygiene, cough etiquette, staying home when febrile/unwell, ventilation and a well-fitting mask when transmission risk is high or local guidance recommends it.
- Serology does not guide acute common-cold management; culture is also too slow for routine clinical decision-making
- Personal hygiene: Hand washing, wearing masks
- Sleep: Participants with < 7 hours of sleep were 2.94× more likely to develop a cold; those with < 92% sleep efficiency were 5.50× more likely [1]
- Sleep quality and quantity are independent predictors, even after controlling for antibody titres, demographics, BMI, psychological variables, etc.
- Influenza vaccination (see Section 8)
Exam Factoid — Sleep vs Vitamin C
The lecture's quiz favours eight hours of sleep over daily vitamin C. More precisely, short/inefficient sleep was associated with greater susceptibility in the cited viral-challenge study, whereas routine vitamin C does not reliably prevent colds in the general population. This is not a head-to-head treatment trial. [1]
7. Natural Course & Investigation
Mean resolution 2–3 days, 75th percentile resolution 7 days (cough up to 10 days). [1]
| Symptom | Duration Range |
|---|---|
| Cough | 2–20 days |
| Headache | 1–14 days |
| Hoarseness | 2.5–20 days |
| Muscle ache | 2–14 days |
| Runny nose | 2–14 days |
| Sore throat | 2–14.3 days |
How to interpret these numbers: These ranges came from different lecture sources and are distributions, not deadlines. Nasal/throat symptoms often improve within 7–10 days, while acute cough can normally take 3–4 weeks to settle [14]. Reassess earlier for rapid deterioration, dyspnoea, haemoptysis, dehydration, persistent/high fever or focal chest signs.
"Any investigation needed?" [1] — The lecture poses this as a rhetorical question to emphasise that most simple URTIs need no investigations.
| Scenario | Investigation Indicated? |
|---|---|
| Simple common cold | No — clinical diagnosis |
| Influenza | Test when it will change treatment, infection control or disposition; molecular assays are preferred for hospitalized patients, while a negative low-sensitivity antigen test does not exclude influenza [17] |
| Pharyngitis | Follow the local GAS pathway: viral features usually need no GAS test; RADT/culture when indicated, with culture confirmation after a negative RADT in symptomatic children ≥3 years [10] |
| Suspected pneumonia | CXR, sputum culture, blood tests |
| Prolonged or atypical course | Guided by clinical suspicion (CXR, CBC, CRP, etc.) |
8. Management
"Body's immune system is most effective. Curative treatment is usually not needed. Symptomatic treatment — not a pill for every illness/symptom — evidence-based — benefit vs. harm." [1]
"Antibiotics and steroids are not doing any good for viral URTI. Side effects of drugs. Antibiotic resistance." [1]
| Treatment | Evidence | Notes |
|---|---|---|
| Paracetamol | Can reduce pain/fever | Use an age/weight-appropriate dose; check combination products to avoid duplicate dosing |
| NSAID (ibuprofen) | Alternative when suitable; not universally “more effective” | Consider GI, renal, cardiovascular, pregnancy and dehydration risks |
| Aspirin | Contraindicated in children with influenza | Risk of Reye's Syndrome (acute hepatic encephalopathy) |
| Medicated lozenges (adults) | May reduce sore-throat pain by a small amount | Check active ingredient and contraindications [11] |
| Steroids | Do not routinely offer for uncomplicated acute cough/URTI | May be indicated for another diagnosis, such as asthma/croup, not the cold itself [14] |
| Drug Class | Examples | Evidence | Concerns |
|---|---|---|---|
| Opioid antitussives | Codeine; lecture-era pholcodine | Uncertain benefit for URTI cough; respiratory depression, sedation and misuse risks | Pholcodine has been deregistered/banned in Hong Kong since 1 January 2024 [13] |
| Other central/sedating suppressants | Dextromethorphan; diphenhydramine/dexbrompheniramine | Inconsistent evidence; dextromethorphan is not an opioid | Sedation, anticholinergic effects, interactions and overdose risk |
| Expectorants | Ammonium chloride (MES), ipecacuanha, guaifenesin (Robitussin), squill | Effectiveness not proven by RCT (some evidence for guaifenesin) | High dose → nausea & vomiting |
| Mucolytics | Bromhexine/acetylcysteine examples in the slide | Do not routinely offer for acute URTI cough [14] | Dizziness, headache, GI disturbance |
| Beta-agonists (inhaled/oral) | Salbutamol | Do not offer for acute cough unless an underlying airway disease such as asthma provides a separate indication [14] | Palpitations and tremor |
Safety warnings for children: [1]
- FDA: No cough and cold product with decongestant or antihistamine for kids < 2 years — "serious and possibly life-threatening side effects could occur"
- US manufacturers label OTC cough/cold products “do not use under 4”; age restrictions differ by jurisdiction and product [12]
- Never combine products without checking active ingredients, and use the supplied calibrated dosing device rather than a household spoon
| Treatment | Evidence | Notes |
|---|---|---|
| Non-selective antihistamines (e.g. chlorpheniramine) | May reduce sneezing & rhinorrhoea | Sedating; some benefit in URTI |
| Non-sedating selective antihistamines | Much less effective for URTI nasal symptoms | Better for allergic rhinitis |
| Nasal decongestants | Pseudoephedrine may provide transient relief in adults | Side effects can be serious; PPA is a historical slide example withdrawn in many jurisdictions because of haemorrhagic-stroke risk |
| Topical ipratropium (Atrovent) | Can reduce watery rhinorrhoea in adults and children > 6; it is not primarily a decongestant | Expensive |
| Humidification/saline | Saline drops/spray and cool-mist humidification may ease symptoms | Avoid hot steam/warm-mist burn risk, especially in children [12] |
The slide's “no proven efficacy in children and adults” is too broad: some adults obtain short-term relief, but benefit is modest and adverse effects matter. Avoid oral/topical decongestants in young children; in adults check hypertension/cardiovascular disease, urinary retention, glaucoma, pregnancy and interactions. Limit topical vasoconstrictor sprays to a short course to avoid rebound congestion.
"Shotgun therapy increases side effects." [1]
- Combination cough & cold products contain mixtures of antitussives, antihistamines, expectorants, decongestants
- Multiple active ingredients create a major risk of duplicate dosing and poisoning in children; severe and fatal adverse events have occurred [12]
- Beware of lecture-era ingredients:
- Aspirin (salicylate) in children → Reye's syndrome
- Phenylpropanolamine (PPA) → risk of haemorrhagic stroke (withdrawn in many countries)
- Antihistamine overdose when cold medicine + cough mixture prescribed together
| Treatment | Evidence |
|---|---|
| Vitamin C 1–3 g | No benefit if taken at onset of illness [1] |
| Oral zinc lozenges/syrup | May modestly shorten a cold if started early, but studies are inconsistent. The lecture's > 75 mg/day regimen exceeds the adult tolerable upper intake of 40 mg/day and can cause nausea and, if prolonged, copper deficiency; avoid intranasal zinc because of anosmia reports [18] |
- Hand hygiene and respiratory etiquette reduce contact/droplet spread
- Ventilation and well-fitting masks add protection when exposure risk is high or local guidance recommends them
- Stay home when febrile/systemically unwell; rest and maintain hydration [1]
9. Influenza — A Distinct Entity Within URTIs
"Three types of influenza viruses affecting humans: A, B, and C." [1]
"Criteria of ILI (Influenza-Like Illness): fever ≥ 38°C + cough and/or sore throat." [1]
What the virion diagram is showing: influenza is an enveloped virus with surface glycoprotein spikes around a segmented RNA genome. Haemagglutinin mediates attachment/entry; neuraminidase promotes release of progeny virions and is the target of oseltamivir, zanamivir and peramivir. Influenza A and B drive seasonal disease and are represented in seasonal vaccines; influenza C usually causes sporadic milder illness. The ILI definition is a surveillance case definition, not a diagnostic test.
| Feature | Influenza | Common Cold |
|---|---|---|
| Onset | Abrupt | Gradual |
| Fever | High (≥ 38°C), prominent | Low-grade or absent |
| Systemic symptoms | Severe systemic upset, generalised myalgia | Mild malaise |
| Nasal symptoms | Mild | Prominent |
| Cough | Dry, can be prominent | Irritating, scanty sputum |
| Self-limiting? | Most uncomplicated cases; pneumonia and exacerbation of chronic disease are important complications, especially in high-risk groups | Almost always |
| Diagnosis | Clinical; rapid test not more accurate than clinical Dx | Clinical |
Current-practice correction: influenza testing
The slide's wording reflects older rapid antigen tests. Current CDC guidance says outpatient influenza may be diagnosed clinically when circulating, but all patients admitted with suspected influenza should be tested; rapid molecular assays have about 90–95% sensitivity, while rapid antigen tests have only moderate sensitivity and a negative result may need molecular confirmation [17]. Do not delay empiric antivirals in priority patients while awaiting a result [16].
"Effective in preventing illness, complications, hospitalization and death." [1]
Types shown in the lecture: [1]
| Type | Route | Population |
|---|---|---|
| Inactivated influenza vaccine (IIV) | IM (most) | Depending on brand, from age 6 months |
| Live attenuated influenza vaccine (LAIV) | Intranasal | Age 2–49, except pregnancy, immunocompromise and other product-specific contraindications |
| Recombinant influenza vaccine (RIV) | IM | Age ≥18; contains no egg protein or live influenza virus |
Current Hong Kong 2026–27 programme
Hong Kong SCVPD recommends annual seasonal influenza vaccination for everyone aged 6 months or older without a contraindication. For 2026–27, only trivalent seasonal vaccines should be used; IIV, RIV and LAIV remain recommended types with product-specific age limits and precautions. October–November is considered optimal before the main activity period, and protection takes about 2 weeks to develop [15]. Vaccine effectiveness varies by season, age, outcome and strain match, so the lecture's 40–60% figure is illustrative rather than guaranteed.
Priority groups for influenza vaccination: [1]
The table reflects the lecture and remains broadly aligned with the 2026–27 SCVPD risk groups, but eligibility for government-funded/subsidised vaccination is a separate, season-specific administrative question [15].
| Group | Why |
|---|---|
| Healthcare workers | Prevent nosocomial transmission |
| Institutionalised persons | High-risk setting |
| Age ≥ 50 years | Higher complication risk |
| Chronic medical conditions | Chronic lung/cardiovascular/renal/metabolic disease, obesity (BMI ≥ 30), immunocompromised, chronic neurological conditions |
| Children & adolescents (6 months–18 years) | Higher attack rate, school transmission |
| Pregnant women | Risk to mother and fetus |
| Poultry workers / pig farmers | Zoonotic transmission risk |
| Children/adolescents on long-term aspirin | Risk of Reye's syndrome with influenza |
| Drug | Route | Key safety/use point |
|---|---|---|
| Oseltamivir (Tamiflu®) | Oral | Nausea and vomiting |
| Zanamivir (Relenza®) | Inhaled | Bronchospasm risk; avoid in underlying airway disease |
| Peramivir (Rapivab®) | IV | Single-dose option for selected uncomplicated outpatients; diarrhoea |
| Baloxavir marboxil (Xofluza®) | Oral | Single-dose option for selected uncomplicated outpatients; not recommended in pregnancy/breastfeeding because data are insufficient |
Key points: [1]
- In otherwise healthy outpatients with uncomplicated influenza, starting within 48 hours typically shortens illness by about a day
- Early treatment can reduce illness duration and may reduce some complications
- Start treatment as soon as possible for suspected/confirmed influenza in hospitalized patients, severe/progressive illness or people at higher risk; do not wait for laboratory confirmation [16]
- The 48-hour window mainly governs optional treatment of otherwise healthy outpatients. Severe or hospitalized patients may still benefit when treatment begins later [16]
- Oral/enteric oseltamivir is the routine recommended agent for hospitalized influenza; zanamivir, peramivir and baloxavir are not routine inpatient substitutes [16]
From Maksim's notes / GC 106 context: [3][2]
- Oseltamivir and zanamivir are neuraminidase inhibitors
- Baloxavir is a cap-dependent endonuclease inhibitor (novel mechanism)
- Infection control: Use standard plus droplet precautions for seasonal influenza and appropriate eye protection; follow the current isolation protocol for suspected novel/avian influenza, including airborne precautions for aerosol-generating procedures
From the lecture and supporting ENT material:
| Complication | Mechanism |
|---|---|
| Acute otitis media | Eustachian tube dysfunction → middle ear effusion → secondary bacterial infection [1][5] |
| Acute rhinosinusitis | Mucosal oedema obstructs sinus ostia → trapped secretions → bacterial superinfection [6] |
| Lower respiratory spread | Viral descent → acute bronchitis, bronchiolitis (in infants with RSV), pneumonia |
| Asthma exacerbation | Viral-induced airway hyperreactivity |
| Peritonsillar abscess (quinsy) | Untreated or severe bacterial tonsillitis → abscess formation |
From the past paper (2020 MCQ Q52): A patient with 4 months of yellowish nasal discharge post-URTI + bilateral nasal obstruction + mucopus from middle meatus → this is chronic rhinosinusitis. The first-line treatment is intranasal steroid spray (Answer B). [7]
From the past paper (2023 MCQ Q65): A child with otalgia, hearing loss, fever, erythematous TM post-URTI → acute otitis media (Answer C). [8]
| Condition | Key Distinguishing Features |
|---|---|
| Common cold (URTI) | Nasal symptoms predominate, cough, hoarseness, self-limiting 7–10 days |
| Influenza | Abrupt onset, high fever, severe myalgia, systemic upset > nasal symptoms |
| Possible GAS pharyngitis | Sudden sore throat, fever, no cough, exudates and tender anterior cervical nodes raise probability; Centor supports triage but confirmation/prescribing follows the local pathway |
| Allergic rhinitis | Itchiness prominent, watery rhinorrhoea, sneezing, diurnal variation, atopic history |
| Acute rhinosinusitis | Nasal obstruction/discharge ± facial/dental pain or reduced smell; bacterial cause becomes more likely when several features coexist: > 10 days without improvement, purulence, severe unilateral pain, fever or “double worsening” [19] |
| Pneumonia | Fever, productive cough, tachypnoea, crepitations, consolidation signs |
| Acute epiglottitis | Drooling, toxic, dysphagia, muffled voice, stridor — medical emergency |
| Croup | Barking cough, inspiratory stridor, age 6 months–3 years |
| NPC | Unilateral blood-stained nasal discharge, serous otitis media, cranial nerve palsies in southern Chinese |
| Pertussis | Paroxysmal cough with "whoop," post-tussive vomiting, no fever in paroxysmal phase |
| Infectious mononucleosis (EBV) | Prolonged sore throat, fatigue, generalised lymphadenopathy, hepatosplenomegaly, atypical lymphocytes |
From the lecture slides showing ENT examination images: [1]
Throat examination:
- Observe pharyngeal erythema, tonsillar enlargement, exudates, membrane formation
- Palpate anterior cervical lymph nodes
- Note: Exudates can be viral (EBV, adenovirus) or bacterial — do NOT assume bacterial
Ear examination (otoscopy): [1]
- Normal TM landmarks: cone of light, handle of malleus, umbo, lateral process, pars tensa
- Red, bulging TM → acute otitis media (common complication of URTI, especially in children)
- Dull TM with effusion → otitis media with effusion (OME)
Nasal examination:
- Anterior rhinoscopy / nasal endoscopy
- Look for polyps, foreign body, mucopus from middle meatus (sinusitis), deviated septum
Reading the Three Examination Images
- Anterior nasal inspection: stabilise the forehead and gently elevate the nasal tip to inspect the vestibule/anterior cavity; do not mistake the examiner's finger position for sinus palpation.
- Nasal polyp: the image shows a smooth, rounded, glistening polypoid mass. A typical inflammatory polyp is pale/grey and relatively insensitive, unlike the vascular pink-red inferior turbinate; unilateral or bloody masses need further assessment.
- Normal right tympanic membrane: identify the lateral process and handle of the malleus, the umbo, pars tensa and anteroinferior cone of light. The slide labels posterior on the viewer's left and anterior on the right; orientation changes with the ear examined.
"Antibiotics and Steroids are not doing any good for viral URTI." [1]
"Describe strategies to reduce unnecessary antibiotic treatment for acute upper respiratory tract infections" — this is a specific learning outcome of GC 106. [2]
Strategies to reduce unnecessary antibiotic prescribing in URTI:
- Educate patients on the viral aetiology and self-limiting nature
- Use clinical scoring appropriately (FeverPAIN/Centor) to estimate GAS likelihood, but apply the local testing/prescribing pathway rather than treating a score as a diagnosis [10][11]
- Confirm GAS where the pathway requires it and avoid testing patients with clear viral features; treat confirmed infection or the small high-probability group for whom local guidance supports antibiotics
- Use no-antibiotic or delayed/back-up prescribing with explicit instructions on when to start and when to seek reassessment [11]
- Set realistic expectations — acute cough can last 3–4 weeks; reassurance and safety-netting are therapeutic [14]
- Avoid combination cold preparations — "shotgun therapy" increases side effects without proven benefit
"URIs are common and highly infectious. Not all URT symptoms are caused by infection. Different URIs have different pathogenesis & natural courses. Curative treatments are limited and usually unnecessary. Benefit of symptomatic treatments needs to be balanced against harm. Personal hygiene and influenza vaccine are very important in prevention. Flu anti-viral drugs may be considered in patients with influenza depending on circumstances." [1]
High Yield Summary
- Most URTIs are viral and self-limiting; uncomplicated disease is a clinical diagnosis and rarely needs investigation or antibiotics.
- Before calling it a cold, exclude airway emergencies and important mimics such as pneumonia, asthma/COPD, TB, malignancy, allergic rhinitis and drug-induced cough.
- Yellow nasal discharge and tonsillar exudate do not by themselves establish bacterial infection.
- Centor/McIsaac estimates the likelihood of GAS but does not diagnose it. Testing and no/back-up/immediate antibiotic strategies differ by guideline; follow the local pathway.
- Paracetamol or, when suitable, ibuprofen can relieve pain/fever. OTC cough mixtures have limited evidence and important age-specific safety restrictions; pholcodine is banned in Hong Kong and aspirin should be avoided in children with influenza.
- Hand hygiene reduces cold transmission. Adequate sleep is associated with lower susceptibility; vitamin C started after symptoms begin is not an effective cure.
- Influenza is a distinct syndrome. Vaccinate annually; test hospitalized suspected cases and treat hospitalized, severe/progressive or high-risk patients promptly without waiting for confirmation.
Active Recall - Upper Respiratory Tract Infections
[1] Lecture slides: GC 021. Upper respiratory tract infections.pdf (all pages) [2] Lecture slides: GC 106. Practical issues in antibiotic use.pdf (p2, p37); GC 106. Practical issues in antibotic use [Notes].pdf (p1) [3] Senior notes: Maksim Medicine Notes.pdf (p189 — Influenza section) [4] Senior notes: Ryan Ho Respiratory.pdf (p48 — URTI section) [5] Senior notes: Adrian Lui Pediatrics Notes.pdf (p154–156 — URTI and acute coryza) [6] Lecture slides: CFB WCS29_Common ENT conditions 2023.pdf (p15 — Rhinosinusitis) [7] Past papers: 2020 Fourth Summative Assessment MCQ paper.pdf (Q52) [8] Past papers: 2023 Fourth Summative MCQ.pdf (Q65) [10] US CDC. Clinical Guidance for Group A Streptococcal Pharyngitis (updated 18 November 2025): https://www.cdc.gov/group-a-strep/hcp/clinical-guidance/strep-throat.html [11] NICE. Sore throat (acute): antimicrobial prescribing (NG84): https://www.nice.org.uk/guidance/ng84/chapter/recommendations [12] US FDA. Should You Give Kids Medicine for Coughs and Colds?: https://www.fda.gov/consumers/consumer-updates/should-you-give-kids-medicine-coughs-and-colds [13] Hong Kong Department of Health. Deregistration of pharmaceutical products containing pholcodine with effect from 1 January 2024: https://www.info.gov.hk/gia/general/202312/18/P2023121800439p.htm [14] NICE. Cough (acute): antimicrobial prescribing (NG120): https://www.nice.org.uk/guidance/ng120/chapter/recommendations [15] Hong Kong Centre for Health Protection, SCVPD. Recommendations on Seasonal Influenza Vaccination for the 2026–27 Season in Hong Kong (March 2026): https://www.chp.gov.hk/files/pdf/recommendations_on_seasonal_influenza_vaccination_for_the_2026_27_season_in_hong_kong_mar2026.pdf [16] US CDC. Influenza Antiviral Medications: Summary for Clinicians (10 March 2026): https://www.cdc.gov/flu/hcp/antivirals/summary-clinicians.html [17] US CDC. Overview of Influenza Testing Methods (19 December 2025): https://www.cdc.gov/flu/hcp/testing-methods/index.html [18] NIH Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals: https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ [19] NICE. Sinusitis (acute): antimicrobial prescribing—symptoms and signs (NG79): https://www.nice.org.uk/guidance/ng79/chapter/symptoms-and-signs
GC020 Understanding The Person, Family And Social Determinants
A competency framework emphasizing the integration of a patient's individual identity, family dynamics, and social determinants of health into clinical reasoning and person-centered care.
GC022 Visual Spot Diagnoses - Survival Guide For Primary Care
A clinical reference covering key dermatological and physical examination findings that can be rapidly identified on sight to aid diagnosis and management in the primary care setting.